Tobacco stemming



2 Sheets-Sheet 1 n. 'lull L. N. DIBRELL, JR

TOBACCO STEMMING May 30, 1950 Filed Dec. 1o, 1947 May 30, 1950 L. N.DIBRELL, JR 2,509,488

TOBACCO STEMMING Filed Deo. 10, 1947 2 Sheets-Sheet 2 mmm/l H im Il/llllllllll Patented May 30, 1950 UNITED STATES lA'i'iENT QFFICE TOBACCOSTEMMING Louis N. Dibrell, J r., Danville, Va. Application` December 10,1947, Serial No. 790,835

(Gl. ISI- 130) 15 Claims. 1

The present invention relates to a tobacco stemming` mahne. Moreparticularly, the invention concerned with a` machine of the type inwhich` a conveyor serves to. present` the butt ends of the stems ofsuccessive leaves to the bite of a pair of co-acting, stem-drawingrolls, which operate to pull the. stems from the blade portions of the`leaves, the blade, portions being securely held. by the conveyor.

A number of` devices of this nature, have been proposed. A few of. thesehave not been. Sufciently ecient in operation to meet with commercialsuccess. On. the other hand, those machines which have proved capable ofecient operation have generally been characterized by complexity ofdesign and a resulting high cost of manufacture and' maintenance,V thusprecluding utilization by certain tobacco processing plants.

The primary object of my invention is` the provision` of a simple,`inexpensive tobacco stem.- ming machine designed to meet therequirements of tobacco stemming plants. A machine of this nature mustalso be adapted for ease of operation, repaizg, and maintenance and atrthe same time must yet be capable of high efficiency in its stemmingoperation.

rl'he principal feature of my invention is the design of the stemdrawing roll assembly. The rolls of the invention have been especiallydesigned to exert a positive gripping and pulling action, on leaf stemswhile simultaneously producing efcient receiving, engaging orthreadingin, and transverse feeding motions.

It is known to provide both rolls.` of a co-acting pair with conicalends in order to give an enlarged stem, receiving area. It has also beentaught that rolls provided` with spiral guiding surfaces, in theVicinity of their receiving ends will promote transverse stem movementalong the axis of the rolls to the position of the stem drawing surfaceso the rolls. However, so far as is known to me, the drawing operationhas been practically universally dependent upon friction (between stemand rolls) induced by the pres,- sure of smooth or slightly roughenedroll surfaces. While this principle meets with success in some machines,it is entirely undependable in machines in which the rolls do not attainhigh surface velocities (that is, rotation of the order of l6002400revolutions per minute).

I have found that a type of stem drawing roll assembly wherein the rollsmay be generally described as screw-threaded, is capable of highlyerlicient stemming if the threads of the adjacent rolls are made tointer-mesh. A roll assembly of this nature is well-suited for stemdrawing in machines which operate at relatively low speeds, that is, ofthe order of 4004000 revolutions per minute.

The invention is illustrated in the drawllss in which:

Fig. 1 is a plan view of a stemming machine employing the roll design ofthe invention,

Fig. 2 is a side elevation of the machine,

Fig. 3 is an end elevation,

Fig. 4 is an enlarged side elevation of a portion of a pair of rolls in`operative co-acting position, the rolls being in part cut away to show avertical section through their adjacent surfaces,

Fig. 5 is a side elevationof a modiiicationl of the roll assembly ofFigs. 1 4, the rolls being mounted on converging axes,

Fig. 6 is a side elevation of another modification of the roll assembly,each roll being tapered over its entire length,

Fig. 7 is a side elevation of a further modification of the rollassembly wherein each roll is cylindrical over its entire length, therolls being mounted on converging axes,I

Fig. 8 is a side elevation of still another modiiication of the rollassembly wherein each roll has a cylindrical portion and a relativelyslightly tapering conical portion,

Fig. 9 is a side elevation of another roll assembly of modified formwherein one roll is entirely cylindrical and the second roll is taperedover its entire length,

Fig. 10 is a fragmentary axial section through an intermeshing portionof a pair of rolls having a ridge and groove type of threading` asprovided on non-meshing portions of the rolls of` Figs. 1-4,

Fig. 11 is a fragmentary axial section, through a pair of rolls having aland and groove type threadl over both non-meshing and intermeshingportions,

Fig. l2 is a fragmentary axial section, in part in elevation, throughthe intermeshing portion of a pair oflrolls having a land-groove typethread wherein the lands are roughened or knurled, and

Fig. 1'3 is a fragmentary axial section through an intermeshing portionof a pair of rolls having a land-groove type thread with roundedgrooves.

With reference to the drawings, I is an endless conveyor supported ontwo pulley wheels 2 and 3. TheV conveyor and pulleys` may be of anypractical form, and their nature is of no particular importance to theinvention. In the illustrations, the conveyor is shown as a beltprovided with card teeth 4 in customary fashion and mounted on chainsl2. The pulley wheels are provided at their ends with sprockets toaccommodate the chains.

A second endless conveyor 5, also provided with card teeth, ispositioned above the conveyor l on sprocket ended pulleys 5 and 'i sothat tobacco leaves placed on the conveyor i will be engaged by theteeth of both conveyors. The spacing oi the two conveyors may be suchthat there will be an intermeshing of their card teeth on the operativeflight; however, in the preferred arrangement the upper conveyor issufciently spaced from the lower conveyor that the tips of the teeth ofone are in close proximity to and barely clear of the tips of the teethof the other. The pulley wheels 3 and are identical and are respectivelymounted on shafts 8 and E3 on which are keyed identical intermeshinggears lil and il respectively.

The shaft 8 receives power from a driving unit or motor I4 through chaindrive i5 and a driving sprocket i8. It is obvious that the drivingarrangement will result in equal speeds of the conveyors since theidentically sized gears l@ and Il must rotate at the same speed underthe driving influence of the drive mechanism i6., l5, and I6.

The shaft 8 is provided with a bevel gear I8 which co-operates with abevel gear i9 to transmit power to a lower stem-drawing roll 2E! mountedon shaft 2i. Also mounted on shaft 2| is a pinion gear 22 whichintermeshes with an identical pinion gear 22' positioned directly aboveit and keyed to a shaft 23 on which is mounted upper stem-drawing roll2t.

The roll shafts 2l and 23 are journalled at each end in supportingframes 25, 25'; the upper roll 24 being yieldingly forced toward thelower roller 20 by the pressure of adjustable spring retaining means 26and 2l. A portion of the frame 25 on the side of the receiving ends ofthe rolls is offset as at 28 to provide for clearance of the leaf stems,

The rolls 20 and 24 are conical (tapered) for approximately 1/3 of theirlength along the portion indicated by arrows at 29 and are generallycylindrical throughout the remaining portion 30. The entire surface areaof each roll is provided with -a screw-threaded type of configurationcomprising (Fig. 4) grooves 3l and ridges or threads i3 which have theirorigins at the terminus or small end of the roll. These grooves andridges are continuous from their origins to the opposite end of theroll, being therefore, spiral in conformity with the surface of thetapered portion of each roll and helical in conformity with the surfaceof the cylindrical portion.

The grooves 3'! are V-shaped in section throughout, but each ridge,which otherwise is also V-shaped, has its edge or top portion sheared oior out away throughout the stem-gripping portion of the roll to form aflat-topped land 32. Thus, while a normal ridge I3 has a sectionidentical with that of a cone, an altered ridge or land along thecylindrical portion of the roll has a Afiat-topped section identicalwith that of a truncated cone.

Y Therefore, when disposed in intermeshing relationship adjacent eachother (operative position), the lands 32 along the cylindrical and a-part of the tapered portion of each roll extend down into the co-actinggrooves 3l of the opposite roll. This arrangement affords at once bothpositive gripping and positive guiding actions to the tobacco stems fedbetween the rolls. The grooves serve to guide the stems bothlongitudinally and transversely as the rolls turn together, and theco-acting lands serve to retain the stems in position in the grooves.The configuration of the co-acting lands and grooves assures that thestems will not be jammed or cut and mobility of the stems in the bite ofthe rolls will not be hindered. On the other hand, however, thecombination gives sufficient pinching action to produce traction andpromote longitudinal steindrawing movement of the stems.

Stem butt ends will ordinarily be engaged along the tapered portionsnear the point of convergence of the tapered portions of the rolls andthe drawing operation continued and completed along the cylindricalportions of the rolls, The

stem-engaging portion of each roll is normally referred to as thestem-gripping or stem-drawing portion, and the small end of the conicalportion is termed the stem-receiving portion. It is found in actualpractice that depending on the conformity and spacing of the rolls,stem-drawing may take place to a substantial degree along the portion ofthe tapered part of the rolls which is immediately adjacent thecylindrical portion. The point along the rolls where gripping of thestem rst occurs varies with stem size and when, for instance, a largestem has its butt end engaged in the bite of the threads well out alongthe tapered portion, the drawing operation is obviously begun at thattime, and convergence of the vopposed roll surfaces compensates fortaper of the tobacco stem whereby grip of the rolls is maintained on thestem. 'Ihat is to say, as the stem is drawn through the rolls thediameter of that portion of the stem engaged by the rolls becomesincreasingly smaller because of the taper of the stem and the relativemovement of the stem from its large to its small end transverse of therolls, but at the same time, the stem is threaded along the longitudinalIaxes of the rolls whereby the convergence of the roll surfacesapproximates the extent of stem taper so that there is substantiallycontinuous gripping of the stem by the rolls. In other words, the degreeof the convergence of the tapered portions of the rolls is such thatdespite the taper of a stem and its movement both transversely andlongitudinally of the opposed faces of these portions, the stem is atall times substantially in contact with both of said opposed faces.

Therefore, in some instances, stem-drawing will be accomplishedsubstantially or entirely before a stem reaches the cylindrical surfaceof the rolls. Accordingly, it is obvious that the portion of a rollwhich functions to grip and draw stems is determined by the shape,threading and relative positioning of the rolls as well as stern size.In the form of the invention illustrated in Figs. 1 4, which has provedvery practical, the area of each roll which serves in gripping anddrawing stems appears to comprise a portion of the cylindrical surfaceplus a portion of the immediately adjacent tapered surf-ace. In thisform, however, the rolls have their axes substantially parallel, and itis obvious that if the rolls be mounted with their axes in convergingplanes as illustrated in Fig. 5 (wherein 20d and 24a denote lower andupper rolls respectively and 29a indicates tapered portions), theposition along the rolls at which stem-drawing occurs would be changed.

Thus, it follows that stem-drawing may take place along either thetapered portions entirely or the cylindrical portions entirely. In theformer case, it is possible to dispense with the cylindrical portions ofthe rolls (Fig. 6, wherein '20h and 24h denote lower and upper rollsrespectively)` or it may be desirable to` prepareA the entire rolls; incylindrical form and mount them inA converging planes (Fig. 7,`whereinZoo and 2de respectively denote lower and upper rolls)` so` that one endof the roll assembly will serve for stem-receiving and guiding and theopposite end will be closely intermeshed.

The various forms of rolls and roll assemblies shown in the drawings aremerely modifications of the invention used for the purpose ofillustration and are not indicative of any limitation in the apparatus.The rolls may be tapered for one-halfoftheir total length, and theywillprove efficient if tapered over an even greater portion, say fortwothirds of their length with the remaining one-third beingcylindrical. Iir thezlatter case (Fig. 3, wherein lower and upper rolls,20d and" Edd, respectively, have tapered portions 29h) depending on theoverall' dimensions` of the rolls, the taper may be of such gradualdegree that intermeshing of the lands and grooves will occur over alarge part of the tapered portion with the possible result that allstem-drawing will take' place along the conical or tapered portionbefore. the stems ever reach the cylindrical portion. arrangement` maybe preferable in many cases since by means of it the eiect of roll taperin compensating for stem taper will be accentuated.

Thus it is evident that roll form may be varied within a wide range ofdesigns inclusive of those mcdil'lcations in which (c) both rolls aretapered throughout their length, (bi) both rolls are cylindrical intheir entirety, and (ci) one roll of the pair is tapered atleast in partwhile its co-acting roll is entirely cylindrical (lig. 9, 2te and-` 24erespectively being rolls of a coacting pair), the only limiting factorsin each case being that (c) both; rolls are screw-threaded and (b) thethreads of the coasting rolls are made to interrnesh over a substantialportion oi" the rolls.

The design and assembly of the rolls removes any restriction otherwiserequired in operating speeds. Since the rolls are not dependent forstein-drawing upon the production of oertain minimum speeds to create asurface friction greater than a particular minimum value, the e'm :encyof the stemming operation is wholly ndent of the operating speed of thestemdi.M .ing rolls, therein lies the essence of the invention. cientstemming has resulted from varying speeds up to 9Go revolutions perminute.

The noinabove described roll surface has been found most practical, butitis within the scope of the invention to have the ridges and grooves ofany desired shape and; form wherein they will intermesh to produceguiding" pocket or cut into which protrudes an oppositely disposedretaining surface, the combination and :xc-operation of the two elementsserving to give a traction inducing pinch e'eot.

it may sometimes be desirable, for instance, to leave the sharp-edged`ridges or threads along the stezmdrawing portion of the rolls asillustreated in Fig. 1G, the ridges 'seing denoted by the nur and thegrooves by 3 la. The sharpridiges or the lands may be provided with trreverse cuts or notches or otherwise roughened as illustrated in l2,lands being denoted by 32h, grooves by and knurling by fil. rihe termscrew-threaded as used in this disclosure is intended to generallydescriptive of any roll surface having a form in accordance with thegeneral speciiications listed above. The threads may vary in pitch,depth, width, and in cross-l sectional shape. The ridges may, forinstance; be formed with square edges which intermesh with grooveshaving rounded, rather than V-shaped, bottoms asillustrated in Fig. 13where,- in square edged ridges (lands)1 are denoted by 32o' and 48denotes rounded grooves.

The width of the grooves should be suilicient to accommodate the largestsize of stems to be operatedl upon` and deep enough to retain the stems,otherwise, the angle formed by the sides of the threads and grooves mayvary, preferably within the range of 10 to 90. Further, the pitch of thethreads and grooves may vary within the range` 45 to a fraction of l aslong as the threads of a mounted roll assembly are not disposed at anangle of greater than about 30 from the stems as presented to the rolls.

The degree to which the rolls intermesh is made adjustable by thespringwetaining means 2S and 2-1, and the` proper pressure between therolls for a particular operation is determined by the particular typeand moisture content of the tobacco being processed, it being onlynecessary to try several settings in order to determine the spacing foroptimum conditions of operation with any particular lot of tobacco. Itis obvious that the nature and strength ci springs 33 utilized in theretaining means 25 and 2l will also dictate to some extent the propersetting oi the retainers.

As pointed out above, it is within the scope oi the invention that thesize of the rolls, the depth of the grooves, or the angle oi inciden-ceof the threading be varied. However, it has been determined thatefficient rolls may have an overall length of approximately lli incheswith a maX- imum diameter of about 3 inches. When pre pared in thissize, the taper ends at about 5 inches from the receiving end with theremaining 9 inches of the roll being cylindrical and the diameter of;the small or receiving end being 2 inches. Suitable thread size is 1/2inch, the threads being cut to a vertical depth of 1%; of an inch fromthe surface of the lands which are approximately 1/8 of an inch inwidth.

The threading over the tapered stem-receiving portion` 29 of each rollmay comprise, instead of grooves 3l and ridges lf3 as shown in Figs. 1,2 and 4, the same groove and land arrangement as is formed in thesurface of the cylindrical portion, as illustrated in Fig. li whereingrooves 3io and lands 32a are continuous over both the tapered andcylindrical portions. However, since the function of these smallportions of the two rolls is to form between them a stem receivingportion, it is generally preferable and more conducive to properthreadingeinA and guiding of the. stems. that the ridges be `J-shaped togive maximum groove depth.

It is to be understood that the surface configuration of thestem-receiving portion of the rolls is not important to the presentinvention except in the respect that some stem-receiving means beprovided for proper guiding and threading in of the` stems to thenipping or sterndrawng surfaces along the bite of the drawing rolls.Thus, any one of a number of known designs may prove satisfactory forthe surface of the stem-receiving portion of the rolls.

The lower conveyor l is given additional support along the portion onwhich the stemming operation takes place by a table 35, and it is prei.-erable when a chain drive is employed for the conveyor that the `chainor chains ride in grooves along the table, whereby the conveyor issecured against transverse sway and warping. If so desired, the upperconveyor may be steadied by a like retaining surface 355 in order thatthe ends of the card teeth of the two conveyors be forced to remain inclose proximity while the stemming operation is in progress.

In operation, tobacco leaves are fed from a chute or conveyor (notshown) onto the lower conveyor l in such manner that each leaf has itslongitudinal axis (stem) perpendicular to the longitudinal axis of theconveyor with the butt end of each stem extending beyond the edge of theconveyor` adjacent the stem-drawing roller assembly. The leaves areengaged by the card teeth and move with the conveyor in the directionindicated by the arrows (Figs. l and 2). At the point 3l, the card teethof the upper conveyor converge on the leaves so that while the leavesare undergoing the stemming operation, they are held in position on thecard teeth of the lower conveyor by the card teeth of the upperconveyor.

At position 33 the butt ends of the leaf stems are presented in theopening between the tapered ends of the stem-drawing rolls. At or beforethe stems reach position 39, the stems are threaded into one of thegrooves 3! between the ridges or threads I3. From the vicinity of thepoint 39 the stems are securely retained within the grooves 3| by theco-acting lands 32.

The rolls and 24 being geared to turn in opposite directions asindicated by the arrows, (Fig. 3) begin (in the vicinity of 3S) pullingthe stems from the blade portions retained by the card teeth, the stemsfinally being pulled free of the blade portion pass through the bite ofthe rolls and fall from the rolls on the side opposite the conveyorbelts.

While the stem drawing operation is in progress, the drawing rolls areproviding movement of the stems transverse of the long axis of thestems, i. e. in a direction parallel to the long axis of the rolls.This, of course, is the obvious ren sult of the conformation of thelands and grooves, and it is desirable that the transmission of power tothe rolls be so related to the conveyor drive and to the angle ofincidence of the threading on the roll surface that the transverse movenment of the stems (e. g, in the direction paralleling the longitudinalaxes of the rolls) be at the same rate as the movement of the conveyorbelts. The stem. and leaf portions thus have relative longitudinalmovement, but have no relative movement transversely and the precisenessof the stemming operation is enhanced.

The stemmed leaves or blade portions continue their travel with theconveyors until they reach a point approximately at ill where they maybe removed by any desirable type of mechanism.

As noted above, dimensions of the stem drawing rolls may be varied. Itis also to be noted that roll diameter will to some extent determine theproper relative position of the conveyor with respect to the rolls(point of tangency of the rolls) and will thus also determine to someextent the portion of stem length along which stripping of the bladewill be achieved. Therefore, roll size should be selected in accordancewith these factors.

However, it is obvious that the stem drawing rolls are suited foremployment in machines of widely Varying type, and it is recognized thatthey will prove useful with conveyors of other nature than that hereindisclosed. The roll assembly is adapted for use with any conveyor whichwill supply proper gripping of the leaves while serving to accomplishproper presentation to and movement of the leaves with respect to therolls. Likewise, it is not intended that the power and drivingarrangement be a limitation to the use of the drawing rolls of theinvention, as it is obvious that any type of prime mover and powertransmission system may be employed so long as proper relative movementof the essential elements be obtained.

It is to be noted that the simplicity and design of the machine areconducive to ease of disassembly and assembly, and it is a feature ofthe invention that the machine is thus adapted to be moved with facilityfrom one plant to another as required by the seasonal activity invarious tobacco producing regions.

I claim:

1. In a tobacco stemming machine, a pair of co-acting stem drawing rollshaving cooperating screw-threaded surface portions which are at least inpart intermeshing, and means adjacent said rolls for holding the bladeportion of a tobacco leaf while said rolls draw the stem of said leaf.

2. In a tobacco stemming machine, a pair of co-acting rolls havingopposing cooperating screw-threaded surfaces, the threads of said rollsbeing in intermeshing relationship along at least a portion of theopposing surfaces of said rolls', and at least a part of theintermeshing surface portion of each roll being generally cylindrical,and means adjacent said rolls for holding the blade portion of a tobaccoleaf While said rolls draw the stem of said leaf.

3. An assembly as dened in claim 2 wherein the screw threads on thecylindrical intermeshing surface portion of at least one roll compriselands and grooves.

4. In a tobacco stemming machine, a pair of co-acting rolls havinggenerally cylindrical body portions and adjacent tapered stem-receivingportions coaxial therewith, said rolls being provided with cooperatingsurfaces having oppositely pitched screw threads which are inintermeshing relationship along substantial portions of the adjacentfaces of said rolls, and means adjacent said rolls for holding the bladeportion of a tobacco leaf while said rolls draw the stem of said leaf.

5. An assembly as dened in claim 4 wherein the intermeshing portions ofthe surfaces of said rolls are at least in part along said cylindricalbody portions of said rolls.

6. An assembly as dened in `claim 4 wherein the screw threads of each ofsaid rolls extend continuously over at least a part of the taperedstem-receiving portion and at least a part of the cylindrical bodyportion thereof.

7. An assembly as defined in claim 6 wherein the intermeshing part ofthe surface portion of each of said rolls includes -at least a part ofthe surface on the cylindrical body portion thereof.

8. In a tobacco stemming machine, a pair of leo-acting stem-drawingrollshaving stem-receiving portions and stem-drawing portions andprovided with oppositely pitched cooperating screwthreaded surfacesadapted to advance tobacco stems along the axes of said rolls, thescrewthreaded surfaces of said rolls being in intermeshing relationshipalong the stem-drawing portions of the rolls, and means adjacent saidrolls for holding the blade portion of a tobacco leaf while said rollsdraw the stem of said leaf.

9. In a tobacco stemming machine, a pair of co-acting rolls havingco-acting tapered end portions and surfaces provided with cooperatingscrew threads, said threads being in intermes'hing relationship along atleast a portion of said surfaces, said portion including at least a partof said tapered end portions, and means adjacent said rolls for holdingthe blade portion of a tobacco lea-f while said rolls draw the stem ofsaid leaf.

10. An assembly as denecl in claim 9 wherein the screw threads on thetapered intermeshing portion of at least one roll comprise ridges andgrooves.

11. In a tobacco stemming machine, a pair of converging adjacentco-acting screw-threaded rolls, the threads of the rolls being ininterrneshing relationship over at least a portion of the rolls, andmeans adjacent said rolls for holding the blade portion of a tobaccoleaf While said rolls draw the stem of said leaf.

12. In a tobacco stemming machine, a pair of adjacent `co-acting rollsdisposed on converging axes, at least portions of the rolls havingscrewthreaded surfaces, and the threads of said portions being at leastin part in intermeshing relationship, and means adjacent said rolls forholding the blade portion of a tobacco leaf while said rolls draw thestem of said leaf.

13. In a tobacco stemming machine having a leaf conveyor and acooperating stem-drawing roll assembly in spaced relation therewith andoperated in synchronization thereto, an improved stem-drawing rollassembly comprising a pair of co-acting elongated rolls, said rollshaving surface portions provided With screw threads which are at leastin part intermeshing, said conveyor being positioned adjacent said rollsand being adapted to hold the blade portion of a tobacco leaf While saidrolls draw the stern of said leaf.

14. In a tobacco stemming machine, a pair of adjacent co-actingstem-drawing rolls having bodies of circular transverse section andscrew-threads formed on said bodies, said rolls having cooperatingstem-receiving ends, said threads being at least in part in intermeshingrelationship and being in non-meshing relationship at saidstem-receiving ends, and means adjacent said rolls for holding the bladeportion of a tobacco leaf while said rolls draw the stem of said leaf.

15. In a tobacco stemming machine, a pair of adjacent co-acting rolls,said rolls having coacting tapering body portions of circular transversesection and cooperating screw threads formed on the surfaces of saidtapering body portions, said cooperating threads being in intermeshingrelationship along at least a part of said tapering portions', and meansadjacent said rolls for holding the blade portion of a tobacco leafWhile said rolls draw the stern of said leaf.

LOUIS N. DIBRELL, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 750,161 Briggs Jan. 19, 1904996,958 Wallick July 4, 1911 1,267,776 Lawrence May 28, 1918 1,347,403Richter July 20, 1920 1,926,776 Kean Sept. 12, 1933 2,007,236 Zeun July9, 1935 2,119,162 Hartner May 31, 1938 2,160,703 Markley May 30, 19392,303,908 Brashear Dec. 1, 1942 2,359,824 Brashear Oct. 10, 1944 FOREIGNPATENTS Number Country Date 24,930 Germany Nov. 24, 1883

